package mypackage;

import java.util.Random;

public class testclass3 {
    public static void main(String[] args) {
        Random r=new Random();
        char[] chr=new char[52];
        for (int i = 0; i < 52; i++) {
            if(i<26){
                chr[i]=(char)('a'+i);
            }else{
                chr[i]=(char)('A'+i-26);
            }
        }
        String result="";
        for(int i=0;i<4;++i){
            result=result+chr[r.nextInt(52)];
        }
        result=result+r.nextInt(10);
        System.out.println(result);
    }
}
